Chemistry Reference
In-Depth Information
5 catalyzes OKR of racemic benzoins using dioxygen in the presence of a
catalytic amount of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) at 60 1C
(Scheme 9.9).
16
OKR of alcohols other than benzoins has not been reported.
In the same year, Egami and Katsuki reported iron(salan)-catalyzed oxi-
dative coupling of 2-naphthols (Scheme 9.10; described in detail in Section
d
n
4
r
4
n
g
|
1
O
O
O
5
-Fe(OAc)
2
(10 mol%)
Ar
Ar
Ar
Ar
Ar
+
Ar
OH
TEMPO (5 mol%)
hexanes, O
2
, 60 ºC
O
OH
R
2
O
R
3
R
3
OH
R
1
N
N
R
1
= R
2
= R
3
= H
conv. = 76.0, 98% ee
k
rel
= 7.2
R
1
= R
2
= Et, R
3
= H
conv. = 72.0, 94% ee
k
r
el
= 6.7
R
1
= H, R
2
= Cl, R
3
= H
conv. = 67.0, 94% ee
k
t
-Bu
OH
HO
t
-Bu
R
1
= R
2
= Me, R
3
= H
conv. = 66.0, 90% ee
k
rel
= 7.7
R
1
= R
2
= H, R
3
= Me
conv. = 65.0, 95% ee
k
rel
= 10.6
t
-Bu
t
-Bu
r
el
= 8.8
5
.
Scheme 9.9 Iron-catalyzed OKR of benzoins with a chiral Schiff base.
O
2
OO
FeL
HO
2-naphthol
O
O
OH
LFe
FeL
FeL
6
L = salan ligand
7
8
Ph
Ph
(
R
)
HO
HO
H
H
HO
OO
N
N
Fe
O
Ph
O
Ph
HOOH
(
R
)
HO
2
6
Scheme 9.10
Iron(salan)-catalyzed oxidative coupling of 2-naphthols with dioxygen.
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